1. Several epidemiologists conducted a cohort study of the effect of mercury exposure on the development of brain cancer. Subjects were followed for ten years. There were a total of 150,000 people in the study. Among the subjects, 76,000 were exposed to mercury and the rest were not. 52,000 of those exposed to mercury developed brain cancer, and only 1,200 of those unexposed to mercury developed brain cancer. Assume that 30% of people in Rhode Island are exposed to mercury.

a. Set up the two by two table (2 points).

b. What is the Odds Ratio (also interpret; 2 points)?

c. What is the Relative Risk (also interpret; 2 points)?

2. A five year study was conducted among 5,000 men older than 65 years to examine the relationship between heavy alcohol consumption and the onset of atrial fibrillation. The men were assessed each year. Men who drank heavily contributed a total of 12,500 person-years of observation and 250 of those who drank heavily developed atrial fibrillation. A total of 24,000 person-years were observed for the entire study. And 100 men who did not drink heavily developed atrial fibrillation.

a. Set up the two by two table (2 points).

b. What is the Rate Ratio (also interpret; 2 points)?